How to Calculate the Correct Wick Based on Container Diameter
Choosing the right wick is one of the most important decisions when making candles: it influences the uniformity of the burn, safety, fragrance diffusion, and final appearance. A small wick causes the candle to "tunnel" and not use all the wax; a wick that is too large creates a high flame, soot, and overheats the container. Here is a practical, step-by-step method for selecting the wick based on the container diameter and adjusting it according to your wax and fragrance.
What Influences Wick Selection
- Container diameter: main factor. Larger diameter = more wax mass to heat = more robust wick.
- Type of wax: vegetable waxes (soy, coconut) usually need different wicks than paraffin or pillar blends.
- Fragrance and dye percentage: high loads decrease the thermal conductivity of the wax; they typically require hotter wicks.
- Container height and shape: tall or concave containers may require adjustments in wick length and size.
Quick Practical Rule (Starting Point)
Use this guide as a starting point. Wick size numbers vary by manufacturer; always validate with testing.
- Diameters ≤ 5 cm: thin wicks (e.g., cotton size 0–2 or thin wood wick).
- 5–7 cm: small wick (cotton size 2–4).
- 7–9 cm: medium wick (cotton size 6–8).
- 9–11 cm: large wick (cotton size 10–12 or double wick).
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11 cm: double wick, wide wick, or wide wood wicks.
Step-by-Step Method
- Measure the internal diameter of the container in centimeters.
- Choose an initial wick using the practical rule.
- Adjust based on wax and fragrance: if you use a dense wax or +6–10% fragrance, go up half or one size in wick.
- Perform a burn test: fill the container, allow it to cure for the recommended time, and light it. Conduct a 2-hour control burn to evaluate the wax pool.
- Observe and record: flame appearance, pool size, presence of soot or smoke.
- Adjust: if it doesn't reach the edge after 2 hours, go up a size; if the flame is high (>2–3 cm), flickering, or leaves soot, go down a size.
Signs to Watch For in Testing
- Small pool / tunneling: wick too small.
- Uniform pool and clean edge: correct choice.
- High flame and dark smoke: wick too large or excessive fragrance.
- Splattering wax or bubbling: possible overheating.
Practical Examples
- Soy jar 8 cm: start with cotton wick size 6; if the fragrance load is high (+10%), try size 7.
- Decorative candle 10 cm: double wick or cotton size 10–12; for intense colors, consider a double wick.
- Votive 4 cm: thin wick or thin wood wick.
Tips for Makers and Small Productions
- Test each formula: changes in wax, color, or fragrance require new testing.
- Keep a testing logbook: record diameter, wax, fragrance %, wick size, and result. Over time, you'll have your own chart.
- Keep extra wick sizes in stock for quick iteration.
- If the container is thermally delicate (thin glass), avoid oversized wicks.
Quick FAQs
- Can I always use the same wick? No. Diameter, wax, and fragrance change the thermal needs.
- How often should I test? With every change in formula, color, or container.
- What about wood wicks? The logic is similar: adapt the width of the wood to the diameter and consult manufacturer charts.
Conclusion and Next Step
Measuring the container diameter is the first step. Use the practical rule as a starting point, conduct controlled tests, and document each result: this will reduce waste and improve consistency. If you want to learn the entire process with guided practice—from choosing materials and wicks to burn testing and finishing—we invite you to our candle workshops in Barcelona. These are practical sessions held in our studio where you will learn step-by-step and can make your own candles. Check dates and book at: https://vento.barcelona/talleres
